the century - fighting unit

[D B Campbell]

I was under the impression that there is little certainty about who constitutes the primi ordines and that they may in fact that not account for the centurions of the first cohort.

It is usually presented as "fact" that the primi ordines were the centurions of the First Cohort, but it is only a theory. (At least, until 1993 it was only a theory! -- see below.)

The theory certainly seems to be supported (proven even?) by Ross Cowan's inscription (AE 1993, 1364a), which lists the primi ordines et centuriones legionis primae Italicae. The first six names must be the centurions of the First Cohort, because the next five names are preceded by the rubric cohors II. And as the first six names do not have a rubric of their own, we assume that they are the primi ordines. Thanks, Ross!

It's worth noting that H.M.D. Parker believed that the primi ordines included the pilus prior of cohorts II to X, in addition to the six centurions of the First Cohort.

At any rate, regarding five primi ordines, it seems that we've all been duped by the vague testimony of Vegetius!